The invention relates generally to a support or base cup for a liquid container having a hemispherical bottom and more particularly to a base cup having reduced wall thickness and strategically located ribs which provide necessary strength and rigidity to the base cup while significantly reducing cup weight.
Blow molded multiple serving containers for liquids such as soft drinks, beer and carbonated waters have enjoyed significant market success in the last decade. Such success is the result of a confluence of events relating to both technological and manufacturing progress as well as intelligent marketing and ultimately, consumer acceptance.
For such consumer products, disposability resulting from intrinsically low per unit cost is a parameter which has had a major effect on the market for such containers. Blow molding fabrication techniques are partially responsible for initially achieving as well as maintaining such low costs. And orientable thermoplastic polymers are routinely utilized to fabricate containers having wall thicknesses on the order of 10 to 40 mils which readily withstand oftentimes large internal pressures which may be generated by carbonated beverages.
Due to the design flexibility which such materials and processes permit, numerous bottle shapes have been proposed. Certain designs place a premium on aesthetic values and others, perhaps due to the particular fluid or carbonation level of the fluid intended to be contained therein, place overriding importance on structural considerations. A third viewpoint places the greatest importance on the utilization of a minimum of material. One design which successfully responds to all three parameters is a bottle utilizing a hemispherical bottom. Obviously and unfortunately, however, such a bottle will not independently remain upright, either during filling steps in a bottling plant or in the environment of a consumer. This difficulty has been overcome by the addition of a circular base cup which receives the hemispherical bottom of the container and is secured thereto by an adhesive. The base cup maintains the container in a vertical or upright orientation. This two part container configuration has enjoyed extensive commercial success due to its responsiveness to the product needs delineated above.
Examination of the base cup structure itself reveals that one portion is structural and the other portion is cosmetic. The cosmetic portion can generally be defined as the sidewall which provides vertical continuity to the sidewall of the container in that region adjacent the hemispherical bottom portion. The structural portion of the base cup is generally the remainder of the cup which cradles the hemispherical end of the container and maintains it in a vertical orientation. The two regions are substantially exclusive. That is, the sidewall portion provides substantially no structural benefits and the bottom portion likewise does not offer cosmetic or aesthetic benefits. Armed with this knowledge, and the further knowledge that such containers and base cups are fabricated and utilized by the millions, it would appear to be a desirable goal to minimize the size and weight of the base cup in order to minimize material use.
A survey of the prior art reveals little that guides one toward this goal. U.S. Pat. Nos. 3,372,826 and 3,482,724 teach an early base cup design having both circumferential and longitudinal ribbing but it does not address the present goal. U.S. Pat Nos. 3,948,404 and 4,241,839 disclose base cups having inwardly directed lips which engage containers having reentrant grooves disposed about their lower peripheries but do not disclose relevant structure. U.S. Pat. No. 4,170,622 teaches a method of fabricating reinforced blow molded articles which have ribs on their inner surfaces. Numerous other patents relating to rib reinforcing are disclosed and discussed in this patent.